JPH10243596A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a magnetic wedge from being shifted in the axial direction of a stator core by a method wherein the length of the magnetic wedge is so set as to be longer than the axial direction thickness of the stator core and both the end parts of the magnetic wedge are made to protrude from the end surfaces of the stator core and holders for preventing the magnetic wedge from slipping off are attached to the protruding end parts. SOLUTION: The length of a magnetic wedge 25 is so set as to be longer than the axial direction thickness of a stator core 18 and both end parts in the longitudinal direction of the magnetic wedge 25 are made to protrude from both end surfaces in the axial direction of the stator core 18. Then holders 26 are attached to both end parts in the longitudinal direction of the magnetic wedge 25. It is to be noted that, in order to avoid the generation of an overcurrent in the holder 26 and avoid the decline of an motor efficiency, the holder 26 is made of nonmagnetic and low conductivity material and formed into a rectangular shape. With this constitution, the magnetic wedge 25 is locked by the holders 26 so as to slip off from a slot 20 and the shift of the magnetic wedge 25 in the axial direction of the stator core 18 can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor having a magnetic wedge inserted in a slot, and more particularly to an improvement in a structure for preventing the magnetic wedge from slipping.

[0002]

2. Description of the Related Art In a brushless motor, a field magnet is provided on a rotor. As a material for forming the magnet, a ferrite-based material has been conventionally used, but recently, a neodymium-based material having a high energy density has been employed for high output and high efficiency. The neodymium-based material has an extremely low electric resistance as compared with the conventional ferrite-based material, and is in the region of a good electric conductor.

On the other hand, during driving of the brushless motor, the magnetic flux density in the gap between the magnet of the rotor and the stator core fluctuates as shown by a two-dot chain line A in FIG. The abrupt change in the magnetic flux density shown in the figure is caused by the presence of the slot opening in the stator core.In the following description, the change in the magnetic flux density due to the presence of the slot opening is referred to as slot ripple. I do. In the figure, the magnet has four poles. In addition, brushless motors usually use PWM for speed control.
As a result, the current supplied to the stator coil pulsates as shown in FIG. 18, and the magnetic flux density generated in the stator coil due to the pulsation current also pulsates.

In the brushless motor that performs the PWM control as described above, the magnetic flux density fluctuates due to the presence of the slot opening and the pulsation of the driving current, and the fluctuation of the magnetic flux density generates an induced electromotive force on the surface of the magnet. As a result, an eddy current flows. The eddy current generated in the magnet reduces the motor efficiency. In particular, when a recent field magnet is formed from a neodymium-based material with high energy density, eddy currents are likely to be generated on the surface of the magnet due to low electric resistance, and the motor efficiency tends to decrease significantly. Becomes

As one of the solutions, a magnetic wedge is inserted into a slot opening of a stator core, and the magnetic wedge is used as shown by a broken line B (permeability μ10) or a solid line C (permeability μ100) in FIG. A configuration is adopted in which the occurrence of eddy current in the magnet is suppressed by reducing the slot ripple or absorbing the fluctuation of the magnetic flux density due to the pulsation of the driving current by using a magnetic wedge.

[0006]

In order for a magnetic wedge to perform its function sufficiently, it must be properly fixed in a predetermined position. However, in the related art, as shown in FIG.
After placing the coil 4 in the slot 2 after addressing the letter-shaped insulating sheet 3, the magnetic wedge 5 is pushed into the slot 2 to be held by the elastic force of the coil 4. It is hardened with varnish. In FIG. 20, reference numeral 6 denotes an insulating wedge for electrically insulating the magnetic wedge 5 and the coil 4 from each other.

As described above, in the related art, since the magnetic wedge 5 is held by the elastic force of the coil 4, the magnetic wedge 5 is likely to be displaced in the axial direction of the stator core 1,
There is a problem that the effect cannot be sufficiently obtained. Further, if the magnetic wedge 5 is displaced from the slot 2, in the worst case, the motor may be locked by being caught in a gap between the rotor (not shown) and the stator core 1. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a motor that can prevent a magnetic wedge from being displaced in an axial direction of a stator core or being displaced from a slot in a stator core. .

[0008]

In order to achieve the above object, a motor according to the present invention comprises a stator core having slots and teeth alternately, a stator coil wound around the stator core, and a stator coil inserted into the slot. The magnetic wedge is provided with a length dimension larger than an axial thickness dimension of the stator core, so that an end of the magnetic wedge protrudes from an end face of the stator core, and a protruding end thereof is provided. Characterized in that a holder for preventing slippage is provided. According to this means, since the magnetic wedge is stopped by the holder so as not to come out of the slot, the occurrence of displacement of the stator core in the axial direction is prevented.

In this case, in order to prevent the occurrence of eddy current loss in the holder, it is preferable that the holder is made of a non-magnetic and low-conductive material. In addition, when the holder is attached to the magnetic wedge by fitting, the holder is formed of a heat-shrinkable material in order to prevent the relatively brittle magnetic wedge from being damaged, and the end of the magnetic wedge is formed by heat shrinkage. It is preferred that they fit tightly. In order to more reliably hold the holder against the magnetic wedge, the holder can be interconnected with another adjacent holder or formed integrally with the other holder.

[0010] In order to prevent the magnetic wedge from moving in either of the axial directions of the stator core, it is preferable that the holder is provided at both ends of the magnetic wedge. Also, in order to prevent unnecessary force from acting on the magnetic wedge, the holder is integrally provided with a protrusion fitted to the inner surface of the slot, and the holder can be held by the stator core by this protrusion. Also, in order to omit the insulating wedge provided between the magnetic wedge and the coil, an insulating part inserted between the magnetic wedge and the coil side of the coil is integrally extended with the holder. can do.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a brushless motor will be described below with reference to FIGS. In FIG. 2 showing the entire brushless motor, a motor case has brackets 1 at both ends of a cylindrical case 11.
2, a core 14 of a stator 13 is fitted inside the case 11, and a shaft 17 of a rotor 16 is rotatably supported on ball bearings 15 mounted on brackets 12 on both sides. Have been.

The rotor 16 is of a magnet type. A rotor core 18 is fitted on a shaft 17 of the rotor 16 and a field magnet 19 is mounted on the outer periphery of the rotor core 18. The above magnet 19
Is formed of a neodymium-based material, and is disposed inside the stator core 13 with a slight gap G.

On the other hand, the core 14 of the stator 13 has
As shown in FIG. 1, a large number of slots 20 and teeth 21 are formed alternately on the inner peripheral surface of the stator core 14, and a stator coil 22 is wound around the stator core 14. In this embodiment, the stator 13 has a three-phase four-pole configuration.

In FIG. 4 showing a specific arrangement of the stator coil 22, a substantially U-shaped insulating sheet 23 is provided on the inner surface of the slot 20 of the stator core 14. Both ends are open toward the opening 20a of the slot 20. The stator coil 22 has the coil side 22a in the slot 2
The stator coil 22 is wound around the stator core 14 so as to be housed inside the insulating sheet 23 through the opening 20a of the “0”. After the stator coil 22 is wound around the stator core 14, the insulating wedge 24 is housed in the slot 20. The insulating wedge 24 closes both ends of the insulating sheet 23.

In the slot 20, a magnetic wedge 25 is inserted and arranged at the opening 20a side, and the magnetic wedge 25 and the stator coil 22 are electrically insulated by the insulating wedge 24. I have. The magnetic wedge 25 is formed by mixing a magnetic material such as powdered ferrite into plastic, and is formed with a wide portion 25a corresponding to the wide portion of the slot 20 and an opening 20a of the slot 20, as shown in FIG. It has a substantially T-shaped cross section composed of the matching narrow portion 25b. And this magnetic wedge 2
The length of the length 5 is set to be larger than the thickness of the stator core 18 in the axial direction. With this dimension setting, both ends in the longitudinal direction of the magnetic wedge 25 protrude from both end faces in the axial direction of the stator core 18.

As shown in FIGS. 1, 2, and 7, holders 26 are fitted to both ends of the magnetic wedge 25 in the longitudinal direction. This holder 26 is also shown in FIG. 6 by a non-magnetic and low-conductivity material, for example, a heat-shrinkable plastic, in order to prevent generation of eddy currents in the holder 26 and to prevent a reduction in motor efficiency. Is formed in a rectangular shape. The holder 26 has a substantially T-shaped fitting hole 27 having the same shape as the cross-sectional shape of the magnetic wedge 25.
7 is initially larger than the magnetic wedge 25,
5 is loosely fitted to both ends. And
After the fitting holes 27 are fitted to both ends of the magnetic wedge 25, the holder 26 is contracted by heating, so that the holder 2
6 are firmly fitted to both ends of the magnetic wedge 25. Thus, when the holder 16 is fitted to the magnetic wedge 25, the corners of the magnetic wedge 25, which is relatively brittle in material, are not damaged. Note that the stator 1
3 is varnished after the holder 26 is fitted to the magnetic wedge 25.

As described above, according to this embodiment, since the holder 26 is fitted to both ends of the magnetic wedge 25 in the axial direction, the holder 26 prevents the magnetic wedge 25 from coming out of the slot 20. Can be Therefore, it is possible to prevent the magnetic wedge 25 from being displaced so as to protrude from the slot 20 or from being displaced from the slot 20. Therefore, the function of alleviating the fluctuation of the magnetic flux density of the magnetic wedge 25 can be sufficiently exhibited.

In this case, since the holders 26 are provided at both ends of the magnetic wedge 25 and the stator core 14 is sandwiched between the two holders 26,
The magnetic wedge 25 can be regulated so as not to be displaced in any of the axial directions of the stator core 14, which is more effective. When the brushless motor is arranged vertically (the shaft 17 is oriented in the vertical direction), the holder 26 may be provided only at one end, which is the upper side.

Further, in this embodiment, since the holder 26 is formed of a heat-shrinkable plastic, when the holder 26 is fitted to the magnetic wedge 25, the holder 26 has a loose fitting relationship.
By preventing the corners of the relatively brittle magnetic wedge 25 from being damaged, and by heat-shrinking the holder 26 after fitting, the magnetic wedge 25 can be firmly fitted without causing damage to the magnetic wedge 25. Of the holder 26 can be effectively prevented. FIG. 8 shows a second embodiment of the present invention. The fitting hole 27 of the holder 26 shown in FIG. 8 is configured to be open to the outside at a portion corresponding to the opening 20 a of the slot 20 of the stator core 14. As a result of opening the fitting hole 27 in this manner, the entire holder 26 becomes substantially C-shaped. Therefore, even if the holder 26 is not formed of heat-shrinkable plastic, the holder 26 is elastically deformed so as to expand so that the magnetic wedge 25 is formed. By fitting into
The magnetic wedge 25 can be firmly fitted without damaging it.

FIG. 9 shows a third embodiment of the present invention.
This is because the slot 26 of the stator core 14 is
And a rib 28 as a projection inserted into the opening 20a and fitted to the inner surface thereof is projected along the fitting hole 27. By the way, when the rib 28 is provided, the fitting hole 27 becomes smaller by the thickness of the rib 28, and accordingly, the end of the magnetic wedge 25 fitted in the fitting hole 27 is also made smaller by that amount. It is something to keep.

According to this embodiment, the holder 2 is fitted by fitting the rib 28 into the slot 20 and the opening 20a.
6 itself is held by the stator core 14, so that even if an external force is applied to the holder 26, the external force can be prevented from acting on the magnetic wedge 24, thus preventing the magnetic wedge 24 from being broken or broken. Useful. In addition, the rolling of the holder 26 and thus the slot 2 of the magnetic wedge 25 are performed.
Rolling within zero can be prevented, and misalignment of the magnetic wedge 25 can be more reliably prevented.

In this case, as in the fourth embodiment of the present invention shown in FIG. 10, by extending the protrusion 29 fitted to the inner surface of the slot 20 in the holder 26, the rolling of the holder 26 can be more reliably performed. Can be prevented. FIG.
As in the fifth embodiment of the present invention shown in FIG.
It is good also as a form which only surrounds 7 from three sides.

As in the sixth embodiment of the present invention shown in FIG. 12, a rib 31 is provided to project from one side of the holder 26, and the rib 31 is fitted to the inner peripheral surface of the stator core 14. Thereby, it is possible to prevent the holder 26 from shifting in the outer peripheral direction of the stator core 14.

FIG. 13 shows a seventh embodiment of the present invention in which holders 26 can be connected to each other. That is, connecting portions 26a and 26b are provided at both ends in the width direction of the holder 26 so as to be staggered in the thickness direction, and one connecting portion 26a is provided with a projection 26c as an engaging portion. And the other connecting part 2
A small hole 26d as an engaged portion is formed in 6b.

Such a holder 26 is provided in each slot 20.
When fitted to the projecting end of the magnetic wedge 25,
The protrusion 26c of FIG. 3a is fitted into the small hole 26d of the connecting portion 26b of the adjacent holder 26, and the holders 26 fitted to the magnetic wedges 25 of the respective slots 20 are connected to each other to be in a state of being connected in an annular shape. You. By connecting a large number of holders 26 to each other in this manner, the displacement of the holder 26 is prevented, so that the displacement of the magnetic wedge 25 can be more reliably prevented.

In this case, as in the seventh embodiment of the present invention shown in FIGS. 14 and 15, a large number of fitting holes 27 are formed in an annular holder ring 31, and each fitting hole 27 is formed in each slot 20.
It is good also as a structure fitted to the end part of the magnetic wedge 25 inserted in. By forming a large number of holders 26 integrally in an annular shape as described above, the magnetic wedge 2 can be more reliably formed.
5 can be prevented.

FIG. 16 shows an eighth embodiment of the present invention, in which a rectangular strip as an insulating portion is attached to one of the two holders 26 fitted to both ends of the magnetic wedge 25. The insulating piece 33 is formed integrally. The insulating piece 33 is inserted between the magnetic wedge 25 and the stator coil 22 to electrically insulate the two. Therefore,
The insulating wedge 24 for insulating between the magnetic wedge 25 and the stator coil 22 becomes unnecessary.

In this case, as in the ninth embodiment of the present invention shown in FIG. 17, a strip-shaped insulating piece 34 as an insulating portion is integrated with two holders 26 fitted to both ends of the magnetic wedge 25. And the two holders 26 are attached to the magnetic wedges 25.
Of the two holders 26 when fitted to both ends of the
4 may be configured to abut each other, so that the insulating piece 34 of each holder 26 insulates one half of each side between the magnetic wedge 25 and the stator coil 22.

The present invention is not limited to the embodiment described above and shown in the drawings. For example, the present invention is not limited to a brushless motor, but can be widely applied to motors provided with magnetic wedges. Various changes can be made.

[0030]

As described above, according to the present invention, the following effects can be obtained. According to the first aspect of the present invention, the position of the magnetic wedge can be prevented by the holder, so that the function of the magnetic wedge can be sufficiently exhibited. According to the second aspect of the present invention, since the holder is formed of a non-magnetic and low-conductivity material, it is possible to prevent an eddy current from being generated in the holder and to prevent a decrease in motor efficiency.

According to the third aspect of the present invention, the holder can be fitted to the magnetic wedge by heat shrinking.
A relatively brittle magnetic wedge can be prevented from being lost.
According to the fourth aspect of the present invention, since the holders are connected to each other or formed integrally, it is possible to more reliably prevent the displacement. According to the fifth aspect of the present invention, since the holder is provided at both ends of the magnetic wedge, the magnetic wedge can be prevented from moving in either of the axial directions. According to the sixth aspect of the present invention, since the holder is provided with the projection fitted to the inner surface of the slot, the holder can be held by the stator core, and the magnetic wedge can be more effectively prevented from being damaged. According to the invention as set forth in claim 7, since the insulating portion inserted into the slot in the holder and interposed between the magnetic wedge and the coil side of the coil is integrally protruded, the gap between the magnetic wedge and the coil is provided. The provided insulating wedge can be omitted.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part showing a first embodiment of the present invention.

FIG. 2 is a vertical sectional side view of a brushless motor.

FIG. 3 is a longitudinal sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a longitudinal sectional view taken along the line IV-IV in FIG. 2;

FIG. 5 is a perspective view of a magnetic wedge.

FIG. 6 is a perspective view of a holder.

FIG. 7 is a perspective view showing a holder fitted to a magnetic wedge.

FIG. 8 is a view corresponding to FIG. 6, showing a second embodiment of the present invention;

FIG. 9 is a view corresponding to FIG. 6, showing a third embodiment of the present invention.

FIG. 10 is a view corresponding to FIG. 6, showing a fourth embodiment of the present invention;

FIG. 11 is a view corresponding to FIG. 6, showing a fifth embodiment of the present invention;

FIG. 12 is a view corresponding to FIG. 6, showing a sixth embodiment of the present invention;

FIG. 13 is a perspective view showing a connection configuration of holders according to a seventh embodiment of the present invention.

FIG. 14 is a partial perspective view of an integrally formed holder according to an eighth embodiment of the present invention.

FIG. 15 is an overall plan view.

FIG. 16 is a perspective view of a holder showing a ninth embodiment of the present invention.

FIG. 17 is a view corresponding to FIG. 16 showing a tenth embodiment of the present invention;

FIG. 18 is a waveform diagram of a current supplied to a stator coil for explaining a conventional defect.

FIG. 19 is a diagram showing a magnetic flux density distribution in a gap between a stator and a rotor.

FIG. 20 is a diagram corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

In the figure, 13 is a stator, 14 is a stator core, 16 is a rotor, 19 is a magnet, 20 is a slot, 21 is a tooth, 22 is an insulating sheet, 24 is an insulating wedge, 25 is an insulating wedge, 25 is a magnetic wedge, 26 is a holder, and 27 is a fitting. Holes, 28 and 30 are ribs, 32 is a holder ring, and 33 and 34 are insulating pieces (insulating portions).
It is.

Claims (7)

[Claims] 1. A stator core having slots and teeth alternately, a stator coil wound around the stator core, and a magnetic wedge inserted into the slot, wherein the length dimension of the magnetic wedge is A motor characterized in that an end of a magnetic wedge is protruded from an end face of a stator core by setting the thickness in the axial direction of the stator core to be larger than the thickness of the stator core, and a holder for preventing the protrusion is provided at the protruding end. 2. The motor according to claim 1, wherein the holder is formed of a non-magnetic and low-conductivity material. 3. The holder is formed of a heat-shrinkable material,
2. The motor according to claim 1, wherein the magnetic wedge is closely fitted to an end of the wedge by heat shrinkage. 4. The motor according to claim 1, wherein the holder is interconnected with another adjacent holder or formed integrally with the other holder. 5. The motor according to claim 1, wherein the holder is provided at both ends of the magnetic wedge. 6. The motor according to claim 1, wherein the holder is provided integrally with a projection fitted to an inner surface of the slot. 7. The holder according to claim 1, wherein an insulating portion inserted into the slot and interposed between the magnetic wedge and a coil side of the coil is integrally extended. Motor as described.